code: def test_vocabularies_are_initialized_even_with_empty_corpora(self):
      parallel_corpora = []
  
      ibm_model = IBMModel(parallel_corpora)
      self.assertEqual(
          len(ibm_model.src_vocab), 1
      )  # addition of NULL token
      self.assertEqual(len(ibm_model.trg_vocab), 0)
  
file_path: nltk/nltk/test/unit/translate/test_ibm_model.py
imports: import unittest
  from collections import defaultdict
  from nltk.translate import AlignedSent, IBMModel
  from nltk.translate.ibm_model import AlignmentInfo
label_desc: Use image node_id 2 for calling the TestIBMModel obj's underlying member method code with example usage: obj.test_vocabularies_are_initialized_even_with_empty_corpora() without return types